Explore the parameters of therapy with neuraminidase-altered autologous or isogenic tumor cells. Using known successful models, evaluate parameters such as cell number, route and schedule of administration, methods and duration of cell storage, and use of tissue culture cells to obtain optimal approaches. Explore potential new model systems for evaluation of this form of immunotherapy. These systems will be required to have high applicability to human cancer; that is, the therapy must be evaluated in the presence of established tumors, with or without prior reduction in tumor size by surgery, radiation, or chemotherapy.